I think Olbermann is there to keep Matthews' gremlins from getting out a running amock.

Crooks and Liars: (with video)

In response to Brian Williams’ supposition during MSNBC’s primary night coverage that recent skits on Saturday Night Live including Sen. Clinton’s guest appearance may have been a factor in Tuesday’s primary results, Tweety almost seizes the opportunity to begin waxing misogynistic once again. Luckily for Matthews, Keith Olbermann was there to stop him, and scolded him in the process. ...

I had wondered about Olbermann's role on election shows. He is great, but he nicely got into a commanding spot quickly. I had thought he was their are a counterbalance. But now I am thinking he is there to keep Matthews in check. Williams is senior, but wouldn't do it. As he rips into women, Scarborough would just smirk away. Brokaw is retired and doesn't need to get stuck with it. And no one else is big enough, tough enough, or willing to go toe to toe with Matthews. That leaves Olbermann, who has great rating, who is willing to challenge people, and who is a strong personality. And as we have seen, he is more and more stepping up to butt in when Matthews goes on a rip, or quickly challenges him afterwards to make him think a bit about going with the first thoughts. It might be my imagination, but it is nice to think he is stepping up for the sake of the viewers out there.